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Thread: Let's Talk Iceland

  1. #91
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    So why is the subsidence rate of the caldera so remarkably linear?
    Last edited by CaptainToonces; 2014-Oct-27 at 03:12 AM.

  2. #92
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    Well, this is kind of like the first Caldera collapse being so well monitored, that isn't an explosive event.

    Let me research this on before chiming in on it, but I suspect that it's related to how the magma pool is draining at a somewhat linear rate.

  3. #93
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    I've found 3 articles and one paper detailing Linear Subsidence of Caldera's. http://adsabs.harvard.edu/abs/2014EGUGA..1612534T

    So it seems that a Linear collapse of Caldera's may actually be more common than destructive collapses. It could be that destructive collapses are precipitated by a phase of Linear Subsidence, that is punctuated by an intense eruption around the Caldera. Aka, Krakatoa and Crater Lake.

  4. #94
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    At about 66 square km, Bįršarbunga still has a ways to go to reach record size.
    Today's EPOD:
    largest lava flow in recorded history, the Skaftareldahraun lava flow in southern Iceland. The flow covers approximately 232 sq mi (600 sq km) with the moss as thick as 1.6 ft (0.5 m) in some places (left). The lava flow was created during the Laki eruption of 1783. This fissure eruption lasted 8 months and resulted in a drop in global temperatures...

  5. #95
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    It seems to me like there's an eruption desperately trying to happen underneath Bartharboonka, but there is so much rock and ice covering it that it's stalled.

    Do we see any melt-water on top of the caldera, or is it still cold enough on top of it?
    Last edited by CaptainToonces; 2014-Nov-04 at 09:31 AM.

  6. #96
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    Quote Originally Posted by CaptainToonces View Post
    Do we see any melt-water on top of the caldera, or is it still cold enough on top of it?
    From the Scientific Advisory Board's Nov 3 report:
    Energy of the geothermal areas in Bardarbunga is now few hundred megawatts and the melting of water is
    estimated around 2 cubic meters per. second.
    Not knowing where the geothermal areas are, this is ambiguous. However the same report series has claimed that heat flux to the base of the ice is increasing.

  7. #97
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    Official subsidence measured yesterday at 44m. So it looks like I will have a better baseline to project out from going forward. It appears to be slowing down slightly, my projected rate would of had it at around 48m by now.

    The subsidence of the Bįršarbunga caldera has reached 44 m which corresponds to 1.1-1.2 km³.
    Additionally some geothermal features outside of the caldera have subsided 5-8m in the last 11 days.

  8. #98
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    Link to the graphs of GPS measurements of the caldera's subsidence. http://www.vedur.is/photos/volcanoes...gps_all_is.png Based on that, I calculated a new rate of about .32 m/day. It had started at around .45m/day. The curve of slowing subsidence can be seen on the graph as well.

  9. #99
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    Going to make my first ever, amateurish volcanic predictions.

    1. It should reach 50m subsidence about Nov 24/25th.
    2. Subsidence will continue along the slowing curve, placing the end of it (and the eruption) out to about mid May 2015.
    3. Total subsidence should reach 74m +-4m.
    4. There should not be a catastrophic caldera collapse (Sorry to disappoint)

  10. #100
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    This from today's SAB report:
    The GPS station in the centre of Bardarbunga show that the subsidence of the caldera has decreased. Other measurements do though show that the volume of the subsidence increases with the same rate as it has done since these measurements started in September. This indicates that the flow of magma from Bardarbunga is not decreasing.
    So apparently there's now a larger area sinking more slowly, rather than just slower subsidence.

  11. #101
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    Holuhraun eruption - fresh video
    Aerial footage adds a good sense of scale to what the stationary camera show.
    That's a large crevice the lava river is gushing out of.

  12. #102
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    Wow. Very impressive.
    Cum catapultae proscriptae erunt tum soli proscript catapultas habebunt.

  13. #103
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    And the seismic activity continues. Huge upheaval of magma is thwarted by giant mountain of ice, what will be the endgame?

  14. #104
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    Fact sheet 28.11.2014:
    Scientists flew over Bardarbunga on Wednesday, 26. November. According to data collected in the flight the total depression of the Bardarbunga caldera is 50 meters and the total volume of the depression about 1.4 cubic kilometre since the seismic activity started in mid-August.

  15. #105
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    Quote Originally Posted by dgavin View Post
    Going to make my first ever, amateurish volcanic predictions.

    1. It should reach 50m subsidence about Nov 24/25th.
    Quote Originally Posted by Squink View Post
    Not bad at all!
    Cum catapultae proscriptae erunt tum soli proscript catapultas habebunt.

  16. #106
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    Thank you! We'll see if my other predictions pan out. Looks like I didn't quite get the slowing rate of subsidence down quite right, but I was close I probably should have used a parabolic curve formula for rate reduction instead of a sinual one.

  17. #107
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    Quote Originally Posted by dgavin View Post
    Thank you! We'll see if my other predictions pan out. Looks like I didn't quite get the slowing rate of subsidence down quite right, but I was close I probably should have used a parabolic curve formula for rate reduction instead of a sinual one.
    or maybe a catenary curve. Or maybe it's all too complex to really predict!

  18. #108
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    As of Jan 6th.
    The GPS station in Bardarbunga caldera show that the caldera continues to subside. The rate of the subsidence continues to slow down and is now around 13 cm per day.
    Total Subsidence at 56m as of Dec 31st. It looks to be slowing down faster then I predicted.

  19. #109
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    Quake frequency is down too.
    Getting some mag 3+ quakes showing up further from the Caldera center now.
    For example, on saturday, mag 3.6, 5 km deep and 11.7 km SE of Bįršarbunga.
    Haven't seen spread in that direction before.

  20. #110
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    Anyone tried to fit the deflation to an exponential of the k ( 1 - e^at) sort?

  21. #111
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    Notes from surveillance flight with LHG to the eruption site, 21 JAN 2015 (PDF)
    Observations from the previous surveillance flight held on 10 JAN had already indicated that the intensity of the eruption had decreased since early DEC 2014. Observations made on 21 JAN not only confirm this, but also indicate that the intensity of the eruption has decreased (markedly) further. The collective evidence is given here
    Comparison of photos of the lava channel on 10 and 21 january show a much decreased stream on the 20th.

    Holuhraun Crater as Big as Iceland’s Tallest Church
    The crater which has formed at the Holuhraun eruption site in the northeastern highlands is now 80 meters (263 feet) tall, higher than the second-tallest building in Iceland and Iceland’s tallest church, Hallgrķmskirkja in Reykjavķk, which measures 74.5 meters. The crater is 100 meters wide and several hundred meters long.
    Not so simple after all, Jan 28: (pdf)
    Comprehensive cross-section measurements from air (on 30. December and 21. January) show however that the lava field has thickened substantially during these three weeks and that the volume of the lava field is now little less than 1.4 km3. The flow of magma, during this period, was just under 100 m3 per second. The intensity of the eruption is
    there for slowly decreasing but hopefully it will be possible to measure the volume of the lava field again later this week, which will give new numbers on the flow of magma.

    jj_0001: GPS broadcast from the caldera went down in december, and AFAIK, they haven't been able to get in there to fix the device yet. That leaves a hole in the data.
    Last edited by Squink; 2015-Jan-28 at 07:01 PM.

  22. #112
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    Vatnajökull just went 10 hours between quakes of mag >0.5. Things are really calming down these past couple weeks. Still magma coming out at vent, but haven't seen big lava fountains for a while either.
    Next day: They just added 3 mag ~1 quakes to that period. Probably took them a while to sort them out from windstorm produced noise. Still, quake activity is much below previous levels.
    Last edited by Squink; 2015-Feb-11 at 03:38 PM.

  23. #113
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    Holuhraun Eruption in Final Days?
    Volcanologist Haraldur Siguršsson predicted in October last year that the eruption in Holuhraun would end on March 4 and it appears his prediction may not be too far off the mark, visir.is reports.

    There has been a significant reduction in the eruption in the last few days and it appears that the lava lake, which was being continuously filled with new lava, is closing.
    Quakes are way down, no visible smoke plume during clear daytime for the past week.

  24. #114
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    Yep activity is down, but not gone altogether. I'm still pulling for another big show from this event. Looking at the eruption history in Iceland, it looks like most of the big ones tend to happen in the spring months, no?

  25. #115
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    THE SCIENTIFIC ADVISORY BOARD OF THE ICELANDIC CIVIL PROTECTION
    Date: 28.02.2015

    The volcanic eruption in Holuhraun, which began on August 31st 2014, has come to an end.

  26. #116
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    Rate of Caldera subsidence down to just 5cm a day. Estimated total subsidence at 62m. I don't think it will reach my predicted 70m - 78m range. Also stopped 2.5 months before I predicted.

  27. #117
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    Pretty good swarm along the Reykjanes ridge today (to the west of Reykjavķk). Six or seven over mag 3 in a 6 hour time frame.
    Holuhraun remains relatively quiet.

  28. #118
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    Actually, the Bartharboonka system (including Holuhraun) is rumbling a bit these days. A mag 3 near the Bartharboonka caldera yesterday, and a light swarm of mag 1's continuing all through the area.

  29. #119
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    Another big swarm at the Reykjanes ridge.
    477 quakes in the past 48 hours. 35 over magnitude 3. Max was magnitude 5.0 at 3.5 km depth.
    Iceland Review is on the story.


    Vatnajökull (Holuhraun etc.) looks like it continues to cool down, with 25 quakes of up to max magnitude 2.

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